I don't have an ink city, but I do have an ink hobo. I think that ink is one of the most unique, special colors that Balenciaga has released. I was a little hesitant about it at first, but I now use my ink bag more than any of my other b-bags. I particularly love its chameleon-like qualities: depending on the environment/setting, it can look so very different.
On top of that, it is incredibly versatile. I feel like I will be able to wear the ink for many seasons to come. It's not too flashy or trendy, or too "of the moment", so I know that I will get a lot of use out of it; I don't think I'll ever look back and say, "oh my goodness, what was I thinking?!"
If you're on the bubble about it, I think you should go for it. It will definitely look great in the city and I think you will get good mileage out of it.